title: The peptide transport system Opt is involved in both nutrition and environmental sensing during growth of Lactococcus lactis in milk.
abstract: Lactococcus lactis is known to take up extracellular peptides via at least three distinct peptide transporters. The well-described oligopeptide transporter Opp alone is able to ensure the growth of L. lactis in milk, while the di- and tripeptide transporter DtpT is involved in a peptide-dependent signalling mechanism. The oligopeptide Opt transporter displays two peptide-binding proteins, OptA and OptS. We previously demonstrated that OptA-dependent transport is dedicated to nutritional peptides, as an optABCDF mutant (of a strain devoid of Opp) has an impaired capacity to grow in milk. Using isogenic peptide transport mutants, this study shows that biosynthesis of the Opt transporter is much less sensitive to downregulation that is dependent on extracellular peptides taken up by DtpT than is Opp biosynthesis; this peptide-dependent regulation relies on the transcriptional repressor CodY. We demonstrate the dual function of the Opt system; while OptA contributes to the bacterial nutrition during growth in milk, OptS is involved in the transport of signalling peptides derived from milk and controlling opp expression. So, these results shed new light on the peptide-dependent regulation relying on two peptide transporters with different specificities: DtpT and Opt (via OptS).
authors.affiliation: Université de Lyon, CNRS UMR 5240, Université Lyon 1, 10 rue Dubois F-69622 Villeurbanne, France.
authors.forename: Mauld
authors.initials: M
authors.lastname: Lamarque
authors.affiliation: Université de Lyon, CNRS UMR 5240, Université Lyon 1, 10 rue Dubois F-69622 Villeurbanne, France.
authors.forename: Dominique
authors.initials: D
authors.lastname: Aubel
authors.affiliation: UMR1319 MICALIS, INRA, Centre de Recherches de Jouy-en-Josas, 78352 Jouy-en-Josas Cedex, France.
authors.forename: Jean-Christophe
authors.initials: JC
authors.lastname: Piard
authors.affiliation: Université de Lyon, CNRS UMR 5240, Université Lyon 1, 10 rue Dubois F-69622 Villeurbanne, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Gilbert
authors.affiliation: UMR1319 MICALIS, INRA, Centre de Recherches de Jouy-en-Josas, 78352 Jouy-en-Josas Cedex, France.
authors.forename: Vincent
authors.initials: V
authors.lastname: Juillard
authors.affiliation: Université de Lyon, CNRS UMR 5240, Université Lyon 1, 10 rue Dubois F-69622 Villeurbanne, France.
authors.forename: Danièle
authors.initials: D
authors.lastname: Atlan
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D013294:Lactococcus lactis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism / Q000502:physiology; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism; D008892:Milk / Q000382:microbiology; D009154:Mutation; D009842:Oligopeptides / Q000378:metabolism*; D015398:Signal Transduction; D013379:Substrate Specificity
chemical_list: D018528:ATP-Binding Cassette Transporters; D001426:Bacterial Proteins; D026901:Membrane Transport Proteins; D009842:Oligopeptides; C086845:dtpT protein, Lactococcus lactis